| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [be] [vb pp] an [noun] | 135 |
|
| 2 | must [be] an [noun] | 110 |
|
| 3 | must [be] [vb pp] [noun] | 58 |
|
| 4 | must [be] [vb pp] an | 11 |
|
